Why does my bike chain keep derailing when I drop off the curb on my bike is there an adjustment I could make.
Without knowing what kind of bike you're talking about it's hard to say. A single speed and multi-speed bike would have different reasons for this happening.
Why does my bike chain keep derailing when I drop off the curb on my bike is there an adjustment I could make.
loosen the back tires bolt... pull your back tire back and tighten the bolt
I am assuming that you have a multispeed bike. The problem can be caused by one of two things, and maybe both. Problem one is that the limit screws on the derailleurs are wrong. These control how far in one direction or the other that the chain can be pushed. The second problem is that over the time you have had the bike, the cables have stretched. This would cause the derailleurs to lose control of the chain. I would guess that it is both problems.
Take you bike to you local bike shop, and have them do a tune up. It should cost about $40, and will fix the problem.